Directions: Make the smallest (or largest) sum by filling in the boxes using the whole numbers 1-9 no more than one time each. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Make the smallest (or largest) difference by filling in the boxes using the whole numbers 1-9 no more than one time each. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Make the smallest (or largest) sum by filling in the boxes using the whole numbers 1-9 no more than one time each. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky

Directions: Make the smallest (or largest) product by filling in the boxes using the whole numbers 1-9 no more than one time each. Note: This problem’s difficulty can be adjusted by altering the number of digits (boxes), picking smallest or largest, or by picking either a positive, negative, or both. Source: Robert Kaplinsky